1. Technical Field
The present invention relates generally to cooling systems for internal combustion engines, and, more particularly, to cooling systems for internal combustion engines also having turbochargers with aftercoolers.
2. Background
Internal combustion engines used to operate heavy mechanical equipment, such as large tractors, generate considerable heat that must be dissipated. If not properly dissipated, heat reduces operating efficiency of the engine, and can ultimately lead to damage of the engine.
It is known to provide engine cooling systems which flow a coolant through the block of the engine to cool the engine. The coolant captures heat from the engine and releases the heat through a radiator in which the coolant passes in heat exchange relationship with air. The radiator includes a series of tubes through which the coolant is pumped, and airflow induced by a fan cools the tubes, and hence the coolant flowing through the tubes. The coolant is pumped through various engine components, such as the engine block, an engine oil cooler or the like, to capture heat from the components.
In the operation of an internal combustion engine, the amount of combustion air that can be delivered to the intake manifold of the engine, for combustion in the engine cylinders, is a limiting factor in the performance of the engine. Atmospheric pressure is often inadequate to supply the required amount of air for proper and efficient operation of an engine.
It is known to use one or more turbochargers for compressing air to be supplied to one or more combustion chambers within corresponding combustion cylinders. The turbocharger supplies combustion air at a higher pressure and higher density than existing atmospheric pressure and ambient density. The use of a turbocharger can compensate for lack of power due to altitude, or to increase the power that can be obtained from an engine of a given displacement, thereby reducing the cost, weight and size of an engine required for a given power output. The turbocharger typically includes a turbine driven by exhaust gases from the engine, and one or more compressors driven by the turbine through a turbocharger shaft common to both the turbine and the compressor or compressors. A stream of exhaust gases from the engine is conducted from the exhaust manifold to the turbine, and the exhaust gas stream passing through the turbine causes a turbine wheel to rotate. Rotation of the turbine wheel rotates the common shaft interconnecting the turbine wheel and one or more compressor wheels in the compressor section, thereby rotating the compressor wheels. Air to be compressed is received in the compressor section, wherein the air is compressed and supplied to the intake air system of the engine.
It is known to condition the boost air flowing from the compressor or compressors to affect the overall turbocharger performance and/or the engine efficiency. In turbochargers having multiple stage compressors, compressing the air in the first compressor significantly raises the temperature of the air, increasing the power required by the second compressor to achieve a desired pressure boost. To overcome the detrimental effects of the increase in temperature, so called xe2x80x9cintercoolersxe2x80x9d have been provided in the flow path between the first compressor outlet and the second compressor inlet. Similarly, so called xe2x80x9caftercoolersxe2x80x9d have been used after the turbocharger in turbochargers having both single stage and multi-stage compressors. The aftercooler cools the compressed air being supplied to the intake manifold, thereby increasing the oxygen content per unit volume, to better support combustion in the cylinders and decrease engine operating temperatures.
It is known to supply coolant from the engine cooling system to circulate through the aftercooler, providing a heat exchange medium for the compressed air also flowing through the aftercooler. Heat from the compressed air stream is captured by the coolant and released in the readiator. Reducing the temperature of the charge air can reduce engine emissions and increase engine efficiency.
In an aftercooler system, it is known to provide a separate coolant circuit from the radiator to the aftercooler, including a separate circuit aftercooler (SCAC) pump for circulating the coolant to the aftercooler. However, the cooling efficiency of such systems have not always met expectations under all operating conditions.
A turbocharged engine cooling system using a two-pass radiator and a separate circuit aftercooler pump in an aftercooler cooling circuit is shown in U.S. Pat. No. 6,158,399.
In view of the engine efficiency and emissions reduction benefits obtained from adequate aftercooling of the combustion air, it is desirable to have an improved cooling system that provides adequate aftercooler cooling under various operating conditions.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect thereof, the present invention provides an internal combustion engine with a block defining a coolant channel, including a coolant channel inlet and a coolant channel outlet. A radiator assembly includes first and second groups of radiator cores, first and second radiator inlets and first and second radiator outlets. The first radiator inlet is coupled to the coolant channel outlet and the first radiator outlet is coupled to the coolant channel inlet. The first radiator outlet is associated with the first group of radiator cores, and the second radiator outlet is associated with the second group of radiator cores. A separate circuit aftercooler pump includes a pump inlet and a pump outlet. The pump inlet is coupled to the second radiator outlet. An aftercooler includes an aftercooler coolant inlet and an aftercooler coolant outlet. The aftercooler coolant inlet is coupled to the pump outlet and the aftercooler coolant outlet is coupled to the second radiator inlet.
In another aspect thereof, the present invention provides a cooling system for an internal combustion engine, with a radiator assembly including a first group of radiator cores and a second group of radiator cores, at least one radiator inlet and first and second radiator outlets. The first radiator outlet is associated with the first group of radiator cores, and the second radiator outlet is associated with the second group of radiator cores. A pump includes a pump inlet and a pump outlet. The pump inlet is coupled to the second radiator outlet. An aftercooler includes an aftercooler coolant inlet and an aftercooler coolant outlet, the aftercooler coolant outlet being coupled to the at least one radiator inlet.
In yet another aspect thereof, the present invention provides a method of cooling an internal combustion engine, having steps of providing an engine cooling circuit, a radiator having first and second groups of radiator cores, an aftercooler, a separate circuit aftercooler cooling circuit, and a heat transfer fluid; cooling the fluid in the radiator; flowing a portion of the fluid from the first group of radiator cores to the engine cooling circuit and back to the radiator; and flowing another portion of the fluid from the second group of radiator cores through the aftercooler and back to the radiator.